Studies will be continued of the regulation by glucocorticoid and thyroid hormones of the transcription of the growth hormone gene in clonal lines of rat pituitary tumor cells. Experiments involving detection, isolation, and characterization of the natural genes for rat growth hormone and prolactin from a recombinant library will be continued. Further analysis of the synthesis and processing by the rat pituitary tumor cells of a precursor of growth hormone mRNA will be performed.